Fix the node repeat bug that leads to the nipype 'stop_on_first_rerun' error.

TEST: I ran two subjects through mindboggle, s1 and s2, and there were no errors. Specifically, I ran s1, then ran s1 again with stop_on_first_rerun, and no errors. I did the same for s2. However, when I ran s1 again with stop_on_first_rerun, I got an error. When I looked at the nipype working directory, I found that there are five functions that do not have the subject name anywhere in its path.

I found out that all of them are downstream of Fetch_ants_data, which did not specify a subject.
To fix this, I will have this function take in a subject name as an argument to force nipype to keep each subject's results separate.